Babies. What, Where, When

Infant is a slightly more formal word for baby, the youngest category of child. The word "infant" derives from the Latin word in-fans, meaning "unable to speak." "Infant" is also a legal term with the (quite different) meaning of minor; that is, any child under the age of legal adulthood. A human infant less than a month old is a newborn infant or a neonate. The term "newborn" includes premature infants and postmature infants, as well as full term newborns.

A newborn's head is very large in proportion to the rest of the body, and the cranium is enormous relative to his or her face. While the adult human skull is about 1/8 of the total body length, the newborn's is twice that. At birth, many regions of the newborn's skull have not yet been converted to bone. These "soft spots" are known as fontanels; and the two largest are the diamond-shaped anterior fontanel, located at the top front portion of the head, and the smaller triangular-shaped posterior fontanel, which lies at the back of the head.